Non-volatile memory and methods for fabricating the same

ABSTRACT

A non-volatile memory including a substrate, source/drain regions, a first insulating layer, a charge storage layer, a second insulating layer, and a conductive layer is provided. The source/drain regions are respectively disposed in the substrate apart from each other. The first insulating layer is disposed on the substrate between the source/drain regions. The charge storage layer is disposed on the first insulating layer. The second insulating layer is disposed on the charge storage layer, and a thickness of a peripheral region of the second insulating layer is greater than a thickness of an internal region of the second insulating layer. The conductive layer is disposed on the second insulating layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a structure of an integrated circuit(IC) and methods for fabricating the same. More particularly, thepresent invention relates to a structure of a non-volatile memory andmethods for fabricating the same.

2. Description of Related Art

A non-volatile memory is characterized by maintaining stored data evenwhen the power is off, and thus has become a mandatory device in manyelectronic products for providing normal operation when the electronicproducts are booted. Recently, the non-volatile memory has been widelyadopted in personal computers (PCs) and other electronic equipment.

FIG. 1 is a schematic cross-sectional view of a conventionalnon-volatile memory. Referring to FIG. 1, the non-volatile memoryincludes a substrate 100, a source region 102 a and a drain region 102 bdisposed in the substrate 100, and a gate stacked structure 112. Thegate stacked structure 112 is constituted by a silicon oxide layer 104,a silicon nitride layer 106, another silicon oxide layer 108, and a gate110 all having a uniform thickness. In the conventional non-volatilememory, one bit is respectively stored in the silicon nitride layer 106around the source region 102 a and the drain region 102 b, such that atwo-bit/cell memory is formed.

However, when programming the conventional two-bit/cell non-volatilememory, the two bits in the same memory cell are mutually affected. Ifone bit has been stored in a part near the drain region in theconventional non-volatile memory, a second-bit effect occurs when areading operation is performed, such that a voltage in the portion wherea high current is expected may drop. In other words, when the memorycell is being read, the existing bit poses a direct impact on the memorycell, thus increasing a barrier and a threshold voltage (Vt) forreading.

In view of the above, the second-bit effect not only substantiallyimplicates the operation of devices, but also reduces the devicereliability. Moreover, because the second-bit effect reduces a sensemargin and a Vt window for operating the left bit and the right bit,thus an operation of multi-level cell memory is more difficult.

One of the current solutions is directed to increasing a drain voltage(Vd) for enhancing a drain-induced barrier lowering (DIBL), and therebythe increased barrier and the increased Vt arisen from the second-biteffect can be decreased. Nevertheless, since a dimension of the deviceis continuously shrinking, an excessive drain voltage will result in theoperation difficulties as well.

SUMMARY OF THE INVENTION

In light of the foregoing, the present invention is directed to anon-volatile memory capable of reducing a second-bit effect andresolving problems derived therefrom.

The present invention is further directed to several methods forfabricating a non-volatile memory capable of preventing crossinterference of two bits in a memory cell of the non-volatile memory,such that the reliability of a memory device is enhanced.

The present invention provides a non-volatile memory including asubstrate, a first insulating layer, a charge storage layer, a secondinsulating layer, and a conductive layer. The first insulating layer isdisposed over the substrate and disposed between the source/drainregions. The second insulationg layer is provided with a peripheralregion and an internal region. The charge storage layer is disposedbetween the first insulating layer and the second insulating layer. And,the peripheral region of the second insulating layer is thicker than theinternal region of the second insulating layer. The conductive layer isdisposed on the second insulating layer.

According to an embodiment of the present invention, the thickness ofthe internal region of the second insulating layer ranges from 80angstrom to 100 angstrom, while the thickness of the peripheral regionof the second insulating layer ranges from 90 angstrom to 120 angstrom.A thickness of the first insulating layer ranges from 50 angstrom to 60angstrom. A thickness of the charge storage layer ranges from 60angstrom to 80 angstrom.

According to an embodiment of the present invention, the firstinsulating layer is a oxide layer that comprising silicon oxide. Thecharge storage layer is a dielectric material provides charge trappingability and the dielectric material is nitride material that comprisingsilicon nitride. The second insulating layer is a oxide layer thatcomprising silicon oxide.

The present invention further provides a method for fabricating anon-volatile memory. The method includes providing a substrate at first.A first insulating layer is formed over the substrate and disposedbetween two source/drain regions. A second insulationg layer is providedwith a peripheral region and a internal region. A charge storage layeris formed between the first insulating layer and the second insulationglayer. The peripheral region of the second insulating layer is thickerthan the internal region of the second insulating layer. A conductivelayer is formed over the second insulating layer.

According to another embodiment of the present invention, the thicknessof the internal region of the second insulating layer ranges from 80angstrom to 100 angstrom, while the thickness of the peripheral regionof the second insulating layer ranges from 90 angstrom to 120 angstrom.A thickness of the first insulating layer ranges from 50 angstrom to 60angstrome. A thickness of the charge storage layer ranges from 60angstrom to 80 angstrom.

According to an embodiment of the present invention, the firstinsulating layer is a oxide layer that comprising silicon oxide. Thecharge storage layer is a dielectric material provides charge trappingability and the dielectric material is nitride material that comprisingsilicon nitride. The second insulating layer is a oxide layer thatcomprising silicon oxide.

The present invention further provides a method for fabricating anon-volatile memory. The method includes forming a stacked structure anda cosuming layer in sequence over a substrate at first. A convertingprocess is performed at a peripheral region of the consuming layer toform a first insulating layer. The consuming layer is removed. Aconductive layer is formed over the stacked layer and the firstinsulating layer.

According to another embodiment of the present invention, the stackedstructure comprises a second insulating layer, a charge storage layer,and a third insulating layer formed in sequence over the substrate. Athickness of the third insulating layer ranges from 80 angstrom to 100angstrom, while a thickness of the first insulating layer ranges from 10angstrom to 20 angstrom. A thickness of the second insulating layerranges from 50 angstrom to 60 angstrom. A thickness of the chargestorage layer ranges from 60 angstrom to 80 angstrom.

According to another embodiment of the present invention, the secondinsulating layer is a oxide layer that comprising silicon oxide. Thecharge storage layer is a dielectric material provides charge trappingability and the dielectric material is nitride material that comprisingsilicon nitride. The third insulating layers is a oxide layer thatcomprising silicon oxide.

According to another embodiment of the present invention, the firstinsulating layers is a oxide layer that comprising silicon oxide.

According to another embodiment of the present invention, the consuminglayer is a polysilicon layer.

According to another embodiment of the present invention, the convertingprocess is an oxidation process.

The present invention further provides a method for fabricating anon-volatile memory. The method includes forming a stacked structure anda cosuming layer in sequence over a substrate at first. A convertingprocess is performed at a peripheral region of the consuming layer toform a first insulating layer. The cosuming layer is removed. A secondinsulating layer is conformally formed on the stacked structure and thefirst insulating layer. A conductive layer is formed on the secondinsulating layer.

According to another embodiment of the present invention, a thickness ofthe first insulating layer ranges from 10 angstrom to 20 angstrom, whilea thickness of the second insulating layer ranges from 80 angstrom to100 angstrom.

According to another embodiment of the present invention, the stackedstructure comprises a third insulating layer and a charge storage layerformed in sequence over the substrate. A thickness of the thirdinsulating layer ranges from 50 angstrom to 60 angstrom. A thickness ofthe charge storage layer ranges from 60 angstrom to 80 angstrom. Thethird insulating layer is a oxide layer that comprising silicon oxide.The charge storage layer is a dielectric material provides chargetrapping ability, and the dielectric material is nitride material thatcomprising silicon nitride.

According to another embodiment of the present invention, the firstinsulating layer is a oxide layer that comprising silicon oxide and thesecond insulating layers is a oxide layer that comprising silicon oxide.

According to another embodiment of the present invention, the consuminglayer is a polysilicon layer.

According to another embodiment of the present invention, the convertingprocess is an oxidation process.

In the present invention, the stacked structure comprising theinsulating layer/the charge storage layer/the insulating layer isdisposed between the conductive layer and the substrate. The insulatinglayer disposed between the conductive layer and the dielectric layer hasa greater thickness of the peripheral region than the thickness of theinternal region of the insulating layer. Accordingly, the thickness ofthe peripheral region of the insulating layer results in a greater DIBL,which effectively reduces the second-bit effect. On the other hand, thenon-volatile memory of the present invention can be further applied to amulti-bit memory device.

In order to make the above and other objects, features and advantages ofthe present invention more comprehensible, several embodimentsaccompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic cross-sectional view of a conventionalnon-volatile memory.

FIG. 2 is a schematic cross-sectional view of a non-volatile memoryaccording to an embodiment of the present invention.

FIGS. 3A and 3B are schematic views illustrating a programming operationof a right bit and a left bit of a memory cell of the non-volatilememory according to the present invention.

FIGS. 4A and 4B are schematic views illustrating an erasing operation ofthe right bit and the left bit of the memory cell of the non-volatilememory according to the present invention.

FIGS. 5A and 5B are schematic views illustrating a reading operation ofthe right bit and the left bit of the memory cell of the non-volatilememory according to the present invention.

FIGS. 6A through 6F are cross-sectional views illustrating a process offabricating the non-volatile memory according to a first embodiment ofthe present invention.

FIGS. 7A through 7G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a second embodiment ofthe present invention.

FIGS. 8A through 8G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a third embodiment ofthe present invention.

FIGS. 9A through 9G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a fourth embodiment ofthe present invention.

DESCRIPTION OF EMBODIMENTS

FIG. 2 is a schematic cross-sectional view of a non-volatile memoryaccording to an embodiment of the present invention.

Referring to FIG. 2, the non-volatile memory includes a substrate 200,source/drain regions 202 a and 202 b, an insulating layer 204, a chargestorage layer 206, another insulating layer 208, and a conductive layer210. The substrate 200 is, for example, a silicon substrate or any otherappropriate semiconductor substrates. The source/drain regions 202 a and202 b are respectively disposed in the substrate 200 apart from eachother.

The insulating layer 204 of the non-volatile memory is disposed on thesubstrate 200 between the source/drain regions 202 a and 202 b. Theinsulating layer 204 is a oxide layer which a material of that is, forexample, silicon oxide, and a thickness of the insulating layer 204, forexample, ranges from 50 angstrom to 60 angstrom, and is preferably about54 angstrom. The charge storage layer 206 is disposed on the insulatinglayer 204. Here, the charge storage layer 206 is a dielectric materialprovides charge trapping ability, and the dielectric material is nitridematerial which is silicon nitride, for example. A thickness of thecharge storage layer 206, for example, ranges from 60 angstrom to 80angstrom, and is preferably about 70 angstrom. The insulating layer 208is disposed on the charge storage layer 206, and the insulating layer208 is a oxide layer which a material of that is silicon oxide, forexample. The conductive layer 210 is disposed on the insulating layer208, and a material of the conductive layer 210 is polysilicon, forexample. Here, the conductive layer 210 serves as a gate of thenon-volatile memory.

Note that the difference between the non-volatile memory proposed in thepresent embodiment and the conventional non-volatile memory lies in thatthe insulating layer 208 of the non-volatile memory in the presentembodiment is not in a uniform thickness. The thickness of theperipheral region (regions 207 a surrounded by dotted lines in FIG. 2)of the insulating layer 208 is greater than the thickness of theinternal region (a region labeled as 207 b in FIG. 2) of the insulatinglayer 208. Here, the thickness of the internal region 207 b of theinsulating layer 208, for example, ranges from 80 angstrom to 100angstrom, and is preferably about 90 angstrom. By contrast, thethickness of the peripheral region 207 a of the insulating layer 208ranges from 90 angstrom to 120 angstrom, for example.

It should be noted that since the non-uniform insulating layer 208 hasthe greater thickness of the peripheral region 207 a than at theinternal region 207 b, a Vt of the non-volatile memory is affected bythe thickness of the insulating layer 208 above the charge storage layer206, resulting in a relatively significant DIBL. Thereby, the second-biteffect is reduced, and a Vt window is increased as well.

The non-volatile memory depicted in FIG. 2 is taken to elaborate aprogranming operation of the non-volatile memory of the presentinvention, an erasing operation thereof, and a reading operationthereof.

Please refer to FIGS. 3A and 3B which are schematic views illustratingthe programming operation of a right bit and a left bit of a memory cellof the non-volatile memory according to the present invention. As shownin FIG. 3A, when the programming operation of the right bit isperformed, a voltage Vg is applied to the conductive layer 210, avoltage Va is applied to the source/drain region 202 a, and a voltage Vbis applied to the source/drain region 202 b. Here, the voltage Vg rangesfrom 5 V to 10 V, the voltage Va is 0 V, and the voltage Vb ranges from4 V to 6 V, for example. Said programming operation is performed byinjecting channel hot electrons (CHEs). In addition, as indicated inFIG. 3B, when the programming operation of the left bit is performed,the voltage Vg is applied to the conductive layer 210, the voltage Va isapplied to the source/drain region 202 a, and the voltage Vb is appliedto the source/drain region 202 b. Here, the voltage Vg ranges from 5 Vto 10 V, the voltage Va ranges from 4 V to 6 V, and the voltage Vb is 0V, for example. Said programming operation is performed by injecting theCHEs as well.

Please refer to FIGS. 4A and 4B which are schematic views illustratingthe erasing operation of the right bit and the left bit of the memorycell of the non-volatile memory according to the present invention. Asshown in FIG. 4A, when the erasing operation of the right bit isperformed, the voltage Vg is applied to the conductive layer 210, thevoltage Va is applied to the source/drain region 202 a, and the voltageVb is applied to the source/drain region 202 b. Here, the voltage Vgranges from −10 V to −5 V, the voltage Va is 0 V, and the voltage Vbranges from 4 V to 6 V, for example. Said erasing operation is performedthrough a band to band hot hole (BTBHH) effect. In addition, asindicated in FIG. 4B, when the erasing operation of the left bit isperformed, the voltage Vg is applied to the conductive layer 210, thevoltage Va is applied to the source/drain region 202 a, and the voltageVb is applied to the source/drain region 202 b. Here, the voltage Vgranges from −10 V to −5 V, the voltage Va ranges from 4 V to 6 V, andthe voltage Vb is 0 V, for example. Said erasing operation is performedthrough the BTBHH effect as well.

Please refer to FIGS. 5A and 5B which are schematic views illustratingthe reading operation of the right bit and the left bit of the memorycell of the non-volatile memory according to the present invention. Asshown in FIG. 5A, when the reading operation of the right bit isperformed, the voltage Vg is applied to the conductive layer 210, thevoltage Va is applied to the source/drain region 202 a, and the voltageVb is applied to the source/drain region 202 b. Here, the voltage Vgranges from 3 V to 5 V, the voltage Va ranges from 1 V to 1.8 V, and thevoltage Vb is 0 V, for example. In addition, as indicated in FIG. 5B,when the reading operation of the left bit is performed, the voltage Vgis applied to the conductive layer 210, the voltage Va is applied to thesource/drain region 202 a, and the voltage Vb is applied to thesource/drain region 202 b. Here, the voltage Vg ranges from 3 V to 5 V,the voltage Vb ranges from 1 V to 1.8 V, and the voltage Va is 0 V, forexample.

Next, several embodiments are enumerated hereinafter for elaboratingmethods for fabricating the non-volatile memory of the presentinvention.

First Embodiment

FIGS. 6A through 6F are cross-sectional views illustrating a process offabricating the non-volatile memory according to a first embodiment ofthe present invention.

First, as shown in FIG. 6A, a substrate 600 is provided. The substrate600 is, for example, a silicon substrate or any other appropriatesemiconductor substrates. Next, an insulating layer 602 is formed on thesubstrate 600. The insulating layer 602 is a oxide layer which amaterial of that is, for example, silicon oxide, and the insulatinglayer 602 is formed by performing a chemical vapor deposition (CVD)process, for example. A thickness of the insulating layer 602, forexample, ranges from 50 angstrom to 60 angstrom, and is preferably about54 angstrom. Next, a charge storage layer 604 is formed on theinsulating layer 602. The charge storage layer 604 is a dielectricmaterial provides charge trapping ability, and the dielectric materialis nitride material which is silicon nitride, for example. The chargestorage layer 604 is formed by performing the CVD process, for example.A thickness of the charge storage layer 604, for example, ranges from 60angstrom to 80 angstrom, and is preferably about 70 angstrom.Thereafter, another insulating layer 606 is formed on the charge storagelayer 604. A material of the insulating layer 606 is, for example,silicon oxide, and the insulating layer 606 is formed by performing theCVD process, for example. A thickness of the insulating layer 606, forexample, ranges from 80 angstrom to 100 angstrom, and is preferablyabout 90 angstrom.

Thereafter, referring to FIG. 6A, a consuming layer 608 is formed on theinsulating layer 606 by performing the CVD process, for example. Theconsuming layer 608 is a polysilicon layer, for example. After that, amask layer 610 is formed on the consuming layer 608. A material of themask layer 610 is, for example, silicon nitride, and a method forforming the mask layer 610 includes carrying out the CVD process, forexample.

Next, referring to FIG. 6B, a patterning process is performed on themask layer 610, the consuming layer 608, the insulating layer 606, thedielectric layer 604, and the insulating layer 602, so as to form astacked structure 611.

Afterwards, referring to FIG. 6C, an isolation layer 612 is formed onthe substrate 600 atthe sides ofthe stacked structure 611. Here,amaterial of the isolation layer 612 is silicon oxide, for example.Thereafter, two source/drain regions 614 are formed in the substrate 600below the isolation layer 612. The source/drain regions 614 are formedby performing an ion implantation process, for example.

Next, referring to FIG. 6D, a portion of the mask layer 610 is removed,so as to cover an internal region 615 of the consuming layer 608 andexpose surfaces of a peripheral region 616 of the consuming layer 608.The portion of the mask layer 610 is removed by performing an etchingprocess, for example.

After that, referring to FIG. 6E, a converting process which is, forexample, an oxidation process is carried out, such that the consuminglayer 608 of the peripheral region 616 is oxidized, and an insulatinglayer 618 is then formed. A thickness of the insulating layer 618 rangesfrom 10 angstrom to 20 angstrom, for example. Here, the insulatinglayers 606 and 618 serve as an upper insulating layer above thedielectric layer 604. After the formation of the insulating layer 618,one etching process is then carried out to remove the mask layer 610 andthe polysilicon layer 608 disposed below the mask layer 610.

Thereafter, referring to FIG. 6F, a conductive layer 620 is formed onthe insulating layers 606 and 618. A material of the conductive layer620 is polysilicon, for example, and the conductive layer 620 is formedby performing the CVD process, for example. The fabrication of thenon-volatile memory is then completed.

Second Embodiment

FIGS. 7A through 7G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a second embodiment ofthe present invention.

First, as shown in FIG. 7A, a substrate 700 is provided. The substrate700 is, for example, a silicon substrate or any other appropriatesemiconductor substrates. Next, an insulating layer 702 is formed on thesubstrate 700. The insulating layer 702 is a oxide layer which amaterial of that is, for example, silicon oxide, and the insulatinglayer 702 is formed by performing the CVD process, for example. Athickness of the insulating layer 702, for example, ranges from 50angstrom to 60 angstrom, and is preferably about 54 angstrom.

Thereafter, referring to FIG. 7A, a charge storage layer 704 is formedon the insulating layer 702. The charge storage layer 704 is adielectric material provides charge trapping ability, and the dielectricmaterial is nitride material which is silicon nitride, for example. Thecharge storage layer 704 is formed by performing the CVD process, forexample. A thickness of the charge storage layer 704, for example,ranges from 60 angstrom to 80 angstrom, and is preferably about 70angstrom. Afterwards, a consuming layer 706 is formed on the chargestorage layer 704 by performing the CVD process, for example. Theconsuming layer is a polysilicon layer, for example. After that, a masklayer 708 is formed on the consuming layer 706. A material of the masklayer 708 is, for example, silicon nitride, and a method for forming themask layer 708 includes carrying out the CVD process, for example.

Next, referring to FIG. 7B, the patterning process is performed on themask layer 708, the consuming layer 706, the charge storage layer 704,and the insulating layer 702, so as to form a stacked structure 709.

Afterwards, referring to FIG. 7C, an isolation layer 710 is formed onthe substrate 700 at the sides of the stacked structure 709. Here, amaterial of the isolation layer 710 is silicon oxide, for example.Thereafter, two source/drain regions 712 are formed in the substrate 700below the isolation layer 710. The source/drain regions 712 are formedby performing the ion implantation process, for example.

Next, referring to FIG. 7D, a portion of the mask layer 708 is removed,so as to cover an internal region 715 of the consuming layer 706 andexpose surfaces of a peripheral region 714 of the consuming layer 706.The portion of the mask layer 708 is removed by performing the etchingprocess, for example.

After that, referring to FIG. 7E, a converting process which is, forexample, an oxidation process is carried out, such that the consuminglayer 706 of the peripheral region 714 is oxidized, and an insulatinglayer 716 is then formed. A thickness of the insulating layer 716 rangesfrom 10 angstrom to 20 angstrom, for example. Next, the etching processis performed to remove the mask layer 708 and the consuming layer 706disposed below the mask layer 708.

Thereafter, referring to FIG. 7F, another insulating layer 718 isconformally formed above the insulating layer 716 and the charge storagelayer 704. The insulating layer 718 is a oxide layer which a material ofthat is, for example, silicon oxide, and the insulating layer 718 isformed by performing the CVD process, for example. A thickness of theinsulating layer 718, for example, ranges from 80 angstrom to 100angstrom, and is preferably about 90 angstrom. Here, the insulatinglayers 716 and 718 serve as the upper insulating layer above the chargestorage layer 704.

After that, referring to FIG. 7G, a conductive layer 720 is formed onthe insulating layer 718. A material of the conductive layer 720 ispolysilicon, for example,. and the conductive layer 720 is formed byperforming the CVD process, for example. The fabrication of thenon-volatile memory is then completed.

Third Embodiment

FIGS. 8A through 8G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a third embodiment ofthe present invention.

First, as shown in FIG. 8A, a substrate 800 is provided. The substrate800 is, for example, a silicon substrate or any other appropriatesemiconductor substrates. Next, an insulating layer 802 is formed on thesubstrate 800. The insulating layer 802 is a oxide layer which amaterial of that is, for example, silicon oxide, and the insulatinglayer 802 is formed by performing the CVD process, for example. Athickness of the insulating layer 802, for example, ranges from 50angstrom to 60 angstrom, and is preferably about 54 angstrom.

Thereafter, referring to FIG. 8A, a charge storage layer 804 is formedon the insulating layer 802. The charge storage layer 804 is adielectric material provides charge trapping ability, and the dielectricmaterial is nitride material which is silicon nitride, for example. Thecharge storage layer 804 is formed by performing the CVD process, forexample. Athickness of the charge storage layer 804, for example, rangesfrom 60 angstrom to 80 angstrom, and is preferably abour 70 angstrom.Thereafter, another insulating layer 806 is formed on the charge storagelayer 804. The insulating layer 806 is a oxide layer which a material ofthat is, for example, silicon oxide, and the insulating layer 806 isformed by performing the CVD process, for example. A thickness of theinsulating layer 806, for example, ranges from 80 angstrom to 100angstrom, and is preferably about 90 angstrom. After that, a mask layer808 is formed on the insulating layer 806. A material of the mask layer808 is, for example, silicon nitride, and a method for forming the masklayer 808 includes carrying out the CVD process, for example.

Next, referring to FIG. 8B, the patterning process is performed on themask layer 808, the insulating layer 806, the charge storage layer 804,and the insulating layer 602, so as to form a stacked structure 809.

Afterwards, referring to FIG. 8C, an isolation layer 810 is formed onthe substrate 800 at the sides of the stacked structure 809. Here, amaterial of the isolation layer 810 is silicon oxide, for example.Thereafter, two source/drain regions 812 are formed in the substrate 800below the isolation layer 810. The source/drain regions 812 are formedby performing the ion implantation process, for example.

Afterwards, referring to FIG. 8D, a portion of the mask layer 808 isremoved, so as to cover a internal region 815 of the second insulatinglayer 806 and expose surfaces of a peripheral region 814 of theinsulating layer 806. The portion of the mask layer 808 are removed byperforming the etching process, for example.

Next, referring to FIG. 8E, another insulating layer 816 is formed abovethe mask layer 808 and the peripheral region 814 of the insulating layer806. A material of the insulating layer 816 is, for example, siliconoxide, and the insulating layer 816 is formed by performing the CVDprocess, for example.

After that, referring to FIG. 8F, a portion of the insulating layer 816is removed, such that an insulating layer 818 remains. The insulatinglayer 818 covers the side regions 814 ofthe insulating layer 806. Athickness ofthe insulating layer 818 ranges from 10 angstrom to 20angstrom, for example. Here, the insulating layers 806 and 818 serve asthe upper insulating layer above the charge storage layer 804. After theformation of the insulating layer 818, the etching process is performedto remove the mask layer 808.

Thereafter, referring to FIG. 8G, a conductive layer 820 is formed onthe insulating layers 806 and 818. A material of the conductive layer820 is polysilicon, for example, and the conductive layer 820 is formedby performing the CVD process, for example. The fabrication of thenon-volatile memory is then completed.

Fourth Embodiment

FIGS. 9A through 9G are cross-sectional views illustrating a process offabricating the non-volatile memory according to a fourth embodiment ofthe present invention.

First, as shown in FIG. 9A, a substrate 900 is provided. The substrate900 is, for example, a silicon substrate or any other appropriatesemiconductor substrates. Next, an insulating layer 902 is formed on thesubstrate 900. The insulating layer 902 is a oxide layer which materialof that is, for example, silicon oxide, and the insulating layer 902 isformed by performing the CVD process, for example. A thickness of theinsulating layer 902, for example, ranges from 50 angstrom to 60angstrom, and is preferably about 54 angstrom. Next, a charge storagelayer 904 is formed on the insulating layer 902. The charge storagelayer 904 is a dielectric material provides charge trapping ability, andthe dielectric material is nitride material which is silicon nitride,for example. The charge storage layer 904 is formed by performing theCVD process, for example. A thickness of the charge storage layer 904,for example, ranges from 60 angstrom to 80 angstrom, and is preferablyabout 70 angstrom. Thereafter, another insulating layer 906 is formed onthe charge storage layer 904. The insulating layer 906 is a oxide layerwhich a material of that is, for example, silicon oxide, and theinsulating layer 906 is formed by performing the CVD process, forexample. A thickness of the insulating layer 906, for example, rangesfrom 80 angstrom to 100 angstrom, and is preferably about 90 angstrom.

Thereafter, referring to FIG. 9A, a consuming layer 908 is formed on theinsulating layer 906 by performing the CVD process, for example. Theconsuming layer is a polysilicon layer, for example. After that, a masklayer 910 is formed on the consuming layer 908. A material of the masklayer 910 is, for example, silicon nitride, and a method for forming themask layer 910 includes carrying out the CVD process, for example.

Next, referring to FIG. 9B, the patterning process is performed on themask layer 910, the consuming layer 908, the insulating layer 906, thecharge storage layer 904, and the insulating layer 902, so as to form astacked structure 911.

Next, referring to FIG. 9C, a portion of the mask layer 910 is removed,so as to cover a intemal region 913 of the consuming layer 908 andexpose surfaces of a peripheral region 912 of the consuming layer 908.The portion of the mask layer 910 is removed by performing the etchingprocess, for example.

As illustrated in FIG. 9D, the converting process which is, for example,an oxidation process is then performed, such that the consuming layer908 of the peripheral region 912 is oxidized for forming an insulatinglayer 914. Another insulating layer 916 is also formed on a surface ofthe substrate 900 at the sides of the stacked structure 911.

Afterwards, referring to FIG. 9E, two source/drain regions 918 areformed in the substrate 900 below the insulating layer 916. Thesource/drain regions 918 are formed by performing the ion implantationprocess, for example. Next, another insulating layer 920 is conformallyformed above the mask layer 910, the insulating layer 914, and theinsulating layer 916. The insulating layer 920 is a oxide layer which amaterial of that is, for example, silicon oxide, and the insulatinglayer 920 is formed by performing the CVD process, for example.

After that, referring to FIG. 9F, a portion of the insulating layer 920is removed, such that an insulating layer 922 remains. The insulatinglayer 922 and the insulating layer 914 together construct anotherinsulating layer 924. A thickness of the insulating layer 924 rangesfrom 10 angstrom to 20 angstrom, for example. Here, the insulatinglayers 906 and 924 serve as the upper insulating layer above the chargestorage layer 904. On the other hand, the insulating layers 922 and 916together form a so-called isolation layer 926. Next, the mask layer 910is removed.

Thereafter, referring to FIG. 9G, a conductive layer 928 is formed onthe insulating layer 924 and the consuming layer 908. A material of theconductive layer 928 is polysilicon, for example, and the conductivelayer 928 is formed by performing the CVD process, for example. Thefabrication of the non-volatile memory is then completed.

To sum up, in the present invention, the stacked structure comprisingthe insulating layer/the charge storage layer/the insulating layer isdisposed between the conductive layer and the substrate. The insulatinglayer disposed between the conductive layer and the charge storage layerhas a greater thickness of the peripheral region than the thickness ofthe internal region of the insulating layer. Accordingly, the thicknessof the peripheral region of the insulating layer results in a greaterDIBL, which effectively reduces the second-bit effect and resolves theproblems derived therefrom. Moreover, the device reliability and the Vtwindow for operating the left bit and the right bit are increased.Furthermore, the non-volatile memory of the present invention can beapplied to a multi-bit memory device as well.

The present invention has been disclosed above in the preferredembodiments, but is not limited to those. It is known to persons skilledin the art that some modifications and innovations may be made withoutdeparting from the spirit and scope of the present invention. Therefore,the scope of the present invention should be defined by the followingclaims.

1. A non-volatile memory, comprising: a substrate; a first insulatinglayer disposed over the substrate and disposed between two source/drainregions; a second insulationg layer provided with a peripheral regionand a internal region; a charge storage layer disposed between the firstinsulating layer and the second insulationg layer, wherein theperipheral region of the second insulating layer is thicker than theinternal region of the second insulating layer; and a conductive layerdisposed over the second insulating layer.
 2. The non-volatile memory asclaimed in claim 1, wherein the thickness of the internal region of thesecond insulating layer ranges from 80 angstrom to 100 angstrom, whilethe thickness of the peripheral region of the second insulating layerranges from 90 angstrom to 120 angstrom.
 3. The non-volatile memory asclaimed in claim 1, wherein a thickness of the first insulating layerranges from 50 angstrom to 60 angstrom.
 4. The non-volatile memory asclaimed in claim 1, wherein a thickness of the charge storage layerranges from 60 angstrom to 80 angstrom.
 5. The non-volatile memory asclaimed in claim 1, wherein the first insulating layer is a oxide layerthat comprising silicon oxide.
 6. The non-volatile memory as claimed inclaim 1, wherein the charge storage layer is a dielectric material. 7.The non-volatile memory as claimed in claim 6, wherein the dielectricmaterial providing charge trapping ability.
 8. The non-volatile memoryas claimed in claim 6, wherein the dielectric material is nitridematerial that comprising silicon nitride.
 9. The non-volatile memory asclaimed in claim 1, wherein the second insulating layer is a oxide layerthat comprising silicon oxide.
 10. A method for fabricating anon-volatile memory, the method comprising: providing a substrate;forming a first insulating layer over the substrate and disposed betweentwo source/drain regions; providing a second insulationg layer having aperipheral region and a internal region; forming a charge storage layerbetween the first insulating layer and the second insulationg layer,wherein the peripheral region of the second insulating layer is thickerthan the internal region of the second insulating layer; and forming aconductive layer over the second insulating layer.
 11. The method forfabricating the non-volatile memory as claimed in claim 10, wherein thethickness of the internal region of the second insulating layer rangesfrom 80 angstrom to 100 angstrom, while the thickness of the peripheralregion of the second insulating layer ranges from 90 angstrom to 120angstrom.
 12. The method for fabricating the non-volatile memory asclaimed in claim 10, wherein a thickness of the first insulating layerranges from 50 angstrom to 60 angstrom.
 13. The method for fabricatingthe non-volatile memory as claimed in claim 10, wherein a thickness ofthe charge storage layer ranges from 60 angstrom to 80 angstrom.
 14. Themethod for fabricating the non-volatile memory as claimed in claim 10,wherein the charge storage layer is a dielectric material and thedielectric material providing charge trapping ability.
 15. The methodfor fabricating the non-volatile memory as claimed in claim 14, whereinthe dielectric material is nitride material that comprising siliconnitride.
 16. A method for fabricating a non-volatile memory, the methodcomprising: forming a stacked structure and a cosuming layer in sequenceover a substrate; performing a converting process at a peripheral regionof the consuming layer to form a first insulating layer; removing theconsuming layer; and forming a conductive layer over the stacked layerand the first insulating layer.
 17. The method for fabricating thenon-volatile memory as claimed in claim 16, wherein the stackedstructure comprises a second insulating layer, a charge storage layer,and a third insulating layer formed in sequence over the substrate. 18.The method for fabricating the non-volatile memory as claimed in claim17, wherein a thickness of the third insulating layer ranges from 80angstrom to 100 angstrom, while a thickness of the first insulatinglayer ranges from 10 angstrom to 20 angstrom.
 19. The method forfabricating the non-volatile memory as claimed in claim 17, wherein athickness of the second insulating layer ranges from 50 angstrom to 60angstrom.
 20. The method for fabricating the non-volatile memory asclaimed in claim 17, wherein a thickness of the charge storage layerranges from 60 angstrom to 80 angstrom.
 21. The method for fabricatingthe non-volatile memory as claimed in claim 17, wherein the chargestorage layer is a dielectric material and the dielectric materialproviding charge trapping ability.
 22. The method for fabricating thenon-volatile memory as claimed in claim 17, wherein the dielectricmaterial is nitride material that comprising silicon nitride.
 23. Themethod for fabricating the non-volatile memory as claimed in claim 16,wherein the converting process is an oxidation process.